One-, two-, and three-photon processes in CdI2 crystal

Single crystal of cadmium iodide (CdI2) was studied under laser excitation from the point of view of optical non-linear materials having potential applications in electronic devices. Low temperature photoluminescence (PL) spectra of the CdI2 crystal were measured. To identify different photon absorption processes in the crystal, the dependences of the PL peak intensity (I-PL) on excitation power (I-0) were investigated. The dependences were found to follow approximately the power law I-PL approximate to I-0(m), where m = 1, 2 and 3 for N-2, ruby and neodymium laser excitations respectively, indicating that the optical responses are due to a first-order, second-order and third-order processes respectively. Photoconductivity measurements in the crystal showed a quadratic dependence of the charge induced on incident laser power, giving evidence of two-photon induced conductivity. The majority carrier lifetime was also studied. (C) 2003 Elsevier B.V. All rights reserved.